DNA Sequences For Regulating Transcription

ABSTRACT

The invention relates to a DNA sequences for regulating transcription of a structural gene encoding a polypeptide in a eukaryotic host cell comprising (a) a first DNA sequence to which RNA polymerase binds which DNA sequence comprises a mRNA initiation site; and further (b) one or more DNA sequence(s) to which RNA polymerase binds with or without a mRNA initiation site. The invention also relates to a DNA construct and an expression vector and a host cell comprising the DNA sequence of the invention.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.11/437,247 filed on May 19, 2006 which is a continuation of U.S.application Ser. No. 10/194,550 filed on Jul. 12, 2002 which claims,under 35 U.S.C. 119, priority or the benefit of Danish application no.PA 2001 01132 filed Jul. 20, 2001 and U.S. provisional application No.60/307,240 filed Jul. 23, 2001, the contents of which are fullyincorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to a control element for increasingtranscription of a structural gene in eukaryotic organisms in connectionwith homologous and heterologous production of polypeptides.

BACKGROUND OF THE INVENTION

Eukaryotic organisms are widely used in industry as host cells forproducing polypeptide for, e.g., pharmaceutical and industrialapplications. The ability to manipulate gene transcription andexpression gives the basis for providing higher production yields.

Conventionally, maximal expression of a gene in a eukaryotic organism isachieved by amplifying in the chromosome an expression cassettecontaining a single promoter operably linked to a gene encoding thepolypeptide of interest and an amplifier selective marker.

Upstream from a structural gene encoding a polypeptide of interest thereis a DNA sequence region (normally referred to as the promoter region)to which RNA polymerase binds. The RNA polymerase catalyses the assemblyof the mRNA complementary to the appropriate DNA strand of thepolypeptide coding region. Most “promoter regions” comprise a RNApolymerase recognition site (often a TATA box) located upstream from thestart of the coding region (structural gene) and the site for accurateinitiation of transcription.

Modification in the “promoter region” may result in enhancedtranscription levels, which again may lead to increased expression andproduction yields.

SUMMARY OF THE INVENTION

The present invention relates to DNA sequences that regulates thetranscription level of eukaryotic host cells, in particular fungalorganisms, especially filamentous fungi, in comparison to thecorresponding parent eukaryotic host cell, so that the transcriptionand/or expression levels are increased.

DEFINITIONS

The terms “DNA sequence” and “nucleic acids sequence” are usedinterchangeably below.

The term “operably linked” is defined herein as a configuration inwhich, e.g., a DNA sequence of the invention is appropriately placed ata position relative to a polypeptide coding DNA sequence such thatincreased transcription levels are obtained.

“Coding sequence” is defined herein as a nucleic acid or DNA sequence,which is transcribed into mRNA and translated into a polypeptide whenplaced under the control of the appropriate control sequences. Theboundaries of the coding sequence are generally determined by a ribosomebinding site located just upstream of the open reading frame at the 5′end of the mRNA and a transcription terminator sequence located justdownstream of the open reading frame at the 3′ end of the mRNA. A codingsequence can include, but is not limited to, genomic DNA, cDNA,semi-synthetic, synthetic, and recombinant nucleic acid sequences.

“Nucleic acid construct” or “DNA construct” is defined herein as anucleic acid molecule, either single- or double-stranded, which isisolated from a naturally occurring gene or which has been modified tocontain segments of nucleic acid which are combined and juxtaposed in amanner which would not otherwise exist in nature. The term nucleic acidconstruct is synonymous with the term expression cassette when thenucleic acid construct contains all the controlling sequences requiredfor expression of a coding sequence.

A “RNA polymerase” is 1) able to recognize a promoter or the likecontrolling elements in the double stranded state of DNA; 2) is able to“burrow into” the DNA duplex at the proper promoter region and unwindthe initiation site of the gene for transcription; 3) copy the gene; 4)stops transcription when it encounters and recognizes terminatorsequence. In eukaryotes three RNA polymerises are known and referred toRNA polymerase I, II, and III. In context of the present invention RNApolymerase II is the most relevant.

That two RNA polymerase binding sites or promoters are “closely linked”or “in proximity” means that no or only few base pairs separate the 5′end of the first RNA polymerase binding site or promoter and theadjacent 3′ end of the second RNA polymerase binding site or promoter.In an embodiment of the invention there may be from 0 to 100 bp inbetween the two RNA polymerase binding sites or promoters. This alsoapplies to the spacing between the second and third RNA polymerasebinding sites or promoters and the third and forth RNA polymerasebinding sites or promoters etc.

The term “terminator” means the site where transcription is concluded.

“Transcription factor”: Many transcription factors are regulatoryproteins that respond to stimuli to the cell (e.g., addition of acarbohydrate) by binding to the TATA box (RNA polymerase recognitionsite) resulting in either activation or repressing of the transcription.

The “Transcription factor binding site” is the DNA site where theTranscription factor binds.

The term “homologous” or “recombinant” expression or production means inthe context of the present invention that the polypeptide in question isexpressed from a gene endogenous to the donor cell or that a DNAconstruct comprising the gene encoding the polypeptide in question isintroduced into the donor cell and expressed from this geneticallymodified donor cell.

The term “donor cell” means the cell from which the gene encoding thepolypeptide is obtained.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 shows a restriction map of pJaL700.

FIG. 2 shows a restriction map of pJaL701.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to DNA sequences that regulate thetranscription levels of eukaryotic host cells, in particular fungalorganisms, especially filamentous fungi, in comparison to thecorresponding parent eukaryotic host cells, so that the transcriptionand/or expression levels are increased.

A DNA sequence of the invention comprises at one or more RNA polymerasebinding sites or regions and one or more mRNA initiation sites. The DNAsequence of the invention may comprise a part of or the whole of one,two, three or more RNA polymerase binding sites or promoters.

A DNA sequence of the invention may further comprise one or more RNApolymerase recognition sites, in particular a TATA box or the like.

Thus, in the first aspect the invention relates to a DNA sequence forregulating transcription of a structural gene encoding a polypeptide ina eukaryotic host cell comprising:

(a) a first DNA sequence to which RNA polymerase binds which DNAsequence comprises a mRNA initiation site; and

(b) one or more DNA sequence(s) to which RNA polymerase binds with orwithout (a) mRNA initiation site(s).

In one embodiment a second DNA sequence as defined under (b) may have aRNA binding region that is substantially identical to the RNA bindingregion defined under (a). Thus, the RNA polymerase binding sites may inan embodiment be tandem sites or repetitive sites. In a preferredembodiment the two or more RNA binding sites (regions) each areconstituted by a part of or the whole of one or more promoter sequences.The RNA binding site of a promoter comprises at least the part requiredfor RNA polymerase binding.

The DNA sequence of the invention normally also includes a RNApolymerase recognition site. This may be a TATA box or the like.However, examples of, e.g., eukaryotic promoters without a TATA box isknown. In an embodiment only the RNA binding site closest to thestructural gene encoding a polypeptide has a RNA polymerase recognitionsite. Said recognition site may be upstream to the structural gene, butdownstream to the second, third or more RNA binding site.

The DNA sequence of the invention may comprise a third DNA sequence towhich RNA polymerase binds. This site or region may in an embodiment bethe whole of a promoter without the mRNA initiation site and may also bewithout a RNA polymerase recognition site. In another embodiment thethird DNA sequence to which the RNA polymerase binds may include aregion comprising a RNA polymerase recognition site and/or mRNAinitiation site. In a preferred embodiment the RNA polymerase bindingsite is the whole or a functional part of the NA2-tpi promoter shown inSEQ ID NO: 1 or the whole or a functional part of the NA2 promoter shownin positions 1 to 510 of SEQ ID NO: 1 or positions 7 to 510 of SEQ IDNO: 1. The second, third or more DNA sequence defined in (b) maypreferably be the whole or a functional part of the NA2-tpi promotershown in SEQ ID NO: 1 with or without a RNA polymerase recognition siteand/or mRNA initiation site or the whole or a functional part of the NA2promoter shown in positions 1 to 510 of SEQ ID NO: 1 or positions 7 to510 of SEQ ID NO: 1, with or without a RNA polymerase recognition siteand/or mRNA initiation site.

In a preferred embodiment of the invention the 3′ end(s) of the second,third and/or more RNA polymerase binding sites are located upstream tothe 5′ end of the first RNA polymerase binding site, which is locatedupstream to the structural gene encoding a polypeptide. Further, in apreferred embodiment the of the invention the third RNA polymerasebinding site is located upstream to the 5′ end of the second RNApolymerase binding site, which is located upstream to the first RNApolymerase binding site which is located upstream to the structural geneencoding a polypeptide. It is within the scope of the invention that oneor more of the DNA sequences defined under (b) comprises an mRNAinitiation site and/or RNA polymerase recognition site.

According to the invention the DNA sequence of the invention forregulating transcription may comprise two or more repetitive RNApolymerase binding sites, in particular 2-5. In an embodiment the RNApolymerase sites are located in tandem or are closely and operablylinked to each other. The RNA binding sites should be located so thattheir function has an impact on the overall transcription level orexpression level. This may be tested by comparing the transcription orexpression levels obtained in comparison to the transcription level of acorresponding parent eukaryotic host cell which only comprises a DNAsequence or promoter as defined under (a) above.

In a preferred embodiment the DNA sequence of the invention forregulating transcription comprises two or three RNA polymerase bindingsites where only the (first) RNA polymerase binding site closest to thestructural gene encoding a polypeptide has an mRNA initiation site andoptionally a RNA polymerase recognition site.

According to the invention the DNA sequence of the invention maycomprise one or more transcription factor binding sites. In anembodiment the transcription factor binding site(s) is (are) locatedupstream to the first RNA polymerase recognition site and/or mRNAinitiation site. In a preferred embodiment the transcription factorbinding site is an Aspergillus transcription factor binding site, suchas a transcription factor binding site derived from A. niger, A.nidulans or A. oryzae, in particular an Aspergillus amyR binding sitedescribed in WO 98/01470 (which is hereby incorporated by reference).

The RNA polymerase binding site may as mentioned above be a promoter, inparticular a promoter selected from the group consisting of the A.oryzae TAKA amylase, NA2-tpi (a hybrid of the promoters from the genesencoding Aspergillus niger neutral alpha-amylase and Aspergillus oryzaetriose phosphate isomerase), and glaA promoters or as described below.

In a preferred embodiment of the DNA sequence of the invention thesecond RNA polymerase binding site is located upstream relative to the5′ end of the first RNA polymerase binding site which includes a mRNAinitiation site. In an embodiment the sites are closely linked. Thisinclude that the sites may be separated by from 0 to 100 bp of eachother, in particular 10-50 bp of each other, especially in 4-30 bp ofeach other.

The parts constituting the DNA sequence of the invention or the wholeDNA sequence of the invention may be artificial or may be derived from aeukaryotic organism, in particular a filamentous fungi, in particular astrain of the genus Aspergillus, Trichoderma, Fusarium or any of theeukaryotic organisms described below in the “Eukaryotic HostCell”-section.

The structural gene may encode any polypeptide. In an embodiment thestructural gene encodes a polypeptide with a biological activity. In apreferred embodiment the structural gene encodes a polypeptideexhibiting enzymatic activity, in particular an enzyme activity selectedfrom the group consisting of an oxidoreductase, transferase, hydrolase,lyase, isomerase, or ligase, such as an enzyme selected from the groupconsisting of aminopeptidase, alpha or beta or maltogenic amylase,CGTase, mannanase, carbohydrase, carboxypeptidase, catalase, cellulase,chitinase, cutinase, deoxyribonuclease, dextranase, esterase,alpha-galactosidase, beta-galactosidase, glucoamylase,alpha-glucosidase, beta-glucosidase, haloperoxidase, invertase, laccase,lipase, mannosidase, mutanase, oxidase, pectin methyl esterase,pectinolytic enzyme, such as pectate lyase, pectin esterase, peroxidase,phytase, polyphenoloxidase, proteolytic enzymes, such as proteases orpeptidases, ribonuclease, transglutaminase, or xylanase.

The invention also relates to a DNA construct comprising a DNA sequenceof the invention for regulating transcription. The DNA construct of theinvention is operative in a eukaryotic host cell as defined below andthe DNA sequences of the invention are operable linked with a structuralgene encoding a polypeptide and a terminator. The DNA construct mayfurther comprise the below control sequences.

The invention also relates to an expression vector comprising a DNAconstruct of the invention. The DNA construct may further comprise asignal peptide coding region. In such embodiment the transcribed andexpression polypeptide will be secreted, in particular into the culturemedium. An expression vector of the invention may comprise a DNAconstruct of the invention wherein the DNA sequence of the invention isoperably linked to a single copy of a structural gene encoding apolypeptide, and optionally leader sequence located upstream of thestructural gene encoding the polypeptide.

Control Sequences

As mentioned above a DNA construct of the invention may further comprisea control sequences. The DNA sequence of the invention may be considereda control sequence and may function as a promoter and may comprise oneor more promoters.

A DNA sequence of the invention for regulating transcription containstranscription and translation control sequences, which mediate theexpression of a polypeptide. The DNA sequence of the invention maycomprise a promoter, a mutant thereof, or a truncated promoter or ahybrid promoter. The promoter may be any nucleic acid sequence, whichshows transcriptional activity in a eukaryotic host cell of choice andmay be obtained from genes encoding extracellular or intracellularpolypeptides either homologous or heterologous to the host cell. Eachpromoter sequence may be native or foreign to the nucleic acid sequenceencoding the polypeptide (structural gene) and native or foreign to theeukaryotic host cell in question. Each control sequence may be native orforeign to structural gene encoding the polypeptide in question to thetranscribed and expression.

Such control sequences include, but are not limited to, a leader, apolyadenylation sequence, a propeptide sequence, a promoter or partthereof, a signal sequence, and a transcription terminator. The controlsequences may be provided with linkers for the purpose of introducingspecific restriction sites facilitating ligation of a nucleic acidsequence encoding the polypeptide in question which is operably linkedto a control element of the invention.

Eukaryotic Promoters

The DNA sequence of the invention for regulating transcription maycomprise a promoter sequence, which contains transcription andtranslation control sequences, which mediate the expression of apolypeptide. A promoter may be any nucleic acid sequence.

Eukaryotic promoters are DNA sequences providing gene expressionregulation at the stage of transcription initiation and may be obtainedfrom genes encoding extracellular or intracellular polypeptides eitherhomologous or heterologous to the host cell in question.

Promoters have a complex block-modular structure and contain numerousshort functional elements such as a transcription factor binding site, aRNA polymerase recognition site, a mRNA initiation site. These sequenceshave no exact uniform location and are dispersed in the 5′-flankingregion up to about 1 kb upstream of the mRNA initiation site wheretranscription starts.

The DNA sequence of the invention, which encompasses at least one RNApolymerase binding site including at least one mRNA initiation site maycomprise a RNA polymerase recognition site that directs the RNApolymerase to the mRNA initiation site. Belonging to these recognitionsites are the TATA box with the consensus sequence TATA(A/T)A(A/T) andlnr with the consensus sequence YYAN(T/A)YY. Transcription initiationbegins with formation of the basal transcription complex in the RNApolymerase binding region. In turn, assembling of the basaltranscription complex at TATA-containing regions/promoters starts withthe recognition of TATA boxes by TATA-binding protein (TBP).

TATA-Box

The TATA box or the like, which may be comprised in the DNA sequence forregulating transcription of the invention can be found in variousspecies ranging from simple eukaryotes such as baker's yeast to morecomplex organisms such filamentous fungi and humans. The TATA boxassists in directing RNA polymerase (RNA polymerase II) to thedownstream mRNA initiation site. The RNA polymerase binds to regions ofDNA, i.e., the RNA polymarase binding site often in general referred toas a promoter. The TATA box is in most cases necessary for transcriptionbecause the RNA polymerase normally cannot recognize the initiationsites on its own. The TATA box directs the RNA polymerase to the m RNAinitiation site once the RNA polymerase has bound to the TATA box. Yetanother problem occurs when the RNA polymerase scans for the TATA box.The RNA polymerase cannot recognize the TATA box on its own. It has touse (a) transcription factor(s) to find the TATA box. After thetranscription factor(s) bind(s) to the TATA box, then the RNA polymerasecan recognize and bind to the TATA box. Then the RNA polymerase binds tothe transcription factor(s), which identify the TATA box. The TATA boxthen guides the RNA polymerase to the mRNA initiation site wheretranscription can begin.

Translation Regulator

The DNA sequence of the invention for regulating transcription mayfurther comprise one or more translation regulating sequences. Thetranslation regulator or leader sequence may be located downstream fromthe first RNA polymerase binding site, in particular downstream to themRNA initiation site and upstream to the structural gene encoding apolypeptide. A suitable leader sequence or translation regulatingsequence may be the triose phosphate isomerase gene (tpi) fromAspergillus nidulans or other Aspergilii.

Filamentous Fungi Promoters

Examples of promoters in filamentous fungal host cells are promotersobtained from the genes encoding Aspergillus oryzae TAKA amylase(EP238023), Rhizomucor miehei aspartic proteinase, Aspergillus nigerneutral alpha-amylase (EP383779), Aspergillus niger acid stablealpha-amylase, Aspergillus niger or Aspergillus awamori glucoamylase(glaA), Rhizomucor miehei lipase, Aspergillus oryzae alkaline protease,Aspergillus oryzae triose phosphate isomerase, Aspergillus nidulansacetamidase, Fusarium oxysporum trypsin-like protease (as described inU.S. Pat. No. 4,288,627, which is incorporated herein by reference), andhybrids thereof. Particularly preferred promoters for use in filamentousfungal host cells are the TAKA amylase, NA2, NA2-tpi (a hybrid of thepromoters from the genes encoding Aspergillus niger neutralalpha-amylase and Aspergillus oryzae triose phosphate isomerase (tpi)),and glaA promoters.

Yeast Promoters

Examples of promotes in yeast host cells are obtained from theSaccharomyces cerevisiae enolase (ENO-1) gene, the Saccharomycescerevisiae galactokinase gene (GAL1), the Saccharomyces cerevisiaealcohol dehydrogenase/glyceraldehyde-3-phosphate dehydrogenase genes(ADH2/GAP), and the Saccharomyces cerevisiae 3-phosphoglycerate kinasegene. Other useful promoters for yeast host cells are described byRomanos et al., 1992, Yeast 8:423-488.

Transcription Terminators

As mentioned above a DNA construct of the invention comprises atranscription terminator sequence, which is a sequence recognized by ahost cell to terminate transcription. The terminator sequence isoperably linked to the 3′ terminus of the structural gene encoding apolypeptide. Any terminator, which is functional in the host cell ofchoice, may be used in the present invention.

Fungus Terminators

Examples of terminators for filamentous fungal host cells are obtainedfrom the genes encoding Aspergillus oryzae TAKA amylase, Aspergillusniger glucoamylase, Aspergillus nidulans anthranilate synthase,Aspergillus niger alpha-glucosidase, and Fusarium oxysporum trypsin-likeprotease.

Yeast Terminators

Examples of terminators for yeast host cells are obtained from the genesencoding Saccharomyces cerevisiae enolase, Saccharomyces cerevisiaecytochrome C (CYC1), or Saccharomyces cerevisiaeglyceraldehyde-3-phosphate dehydrogenase. Other useful terminators foryeast host cells are described by Romanos et al., 1992, Yeast 8:423-488.Terminator sequences are well known in the art for mammalian host cells.

Leader Sequences

The DNA construct of the invention may comprise a suitable leadersequence, a non-translated region of mRNA, which is important fortranslation by the host cell. The leader sequence is operably linked tothe 5′ terminus of the structural gene encoding a polypeptide. Anyleader sequence, which is functional in the host cell of choice, may beused in the present invention.

Fungus Leader Sequences

Preferred leaders for filamentous fungal host cells are obtained fromthe genes encoding Aspergillus oryzae TAKA amylase and Aspergillusoryzae triose phosphate isomerase (tpi).

Yeast Leader Sequences

Suitable leaders for yeast host cells are obtained from theSaccharomyces cerevisiae enolase (ENO-1) gene, the Saccharomycescerevisiae 3-phosphoglycerate kinase gene, the Saccharomyces cerevisiaealpha-factor, and the Saccharomyces cerevisiae alcoholdehydrogenase/glyceraldehyde-3-phosphate dehydrogenase genes (ADH2/GAP).

Polyadenylation Sequences

The DNA construct of the invention may also comprise a polyadenylationsequence, a sequence which is operably linked to the 3′ terminus of thestructural gene encoding the polypeptide and which, when transcribed, isrecognized by the host cell as a signal to add polyadenosine residues totranscribed mRNA. Any polyadenylation sequence, which is functional inthe host cell of choice, may be used in the present invention.

Fungus Polyadenylation Sequences

Preferred polyadenylation sequences for filamentous fungal host cellsare obtained from the genes encoding Aspergillus oryzae TAKA amylase,Aspergillus niger glucoamylase, Aspergillus nidulans anthranilatesynthase, and Aspergillus niger alpha-glucosidase.

Yeast Polyadenylation Sequences

Useful polyadenylation sequences for yeast host cells are described byGuo and Sherman, 1995, Molecular Cellular Biology 15:5983-5990.Polyadenylation sequences are well known in the art for mammalian hostcells.

Signal Peptide

The DNA construct of the invention may comprise a signal peptide-codingregion, which codes for an amino acid sequence linked to the aminoterminus of the polypeptide, which can direct the expressed protein intothe cell's secretory pathway. The 5′ end of the coding sequence of thestructural gene may inherently contain a signal peptide-coding regionnaturally linked in translation reading frame with the segment of thecoding region, which encodes the secreted protein. Alternatively, the 5′end of the coding sequence may contain a signal peptide-coding region,which is foreign to that portion of the coding sequence, which encodesthe secreted protein. The foreign signal peptide-coding region may berequired where the coding sequence does not normally contain a signalpeptide-coding region. Alternatively, the foreign signal peptide-codingregion may simply replace the natural signal peptide-coding region inorder to obtain enhanced secretion of the protein(s) relative to thenatural signal peptide-coding region normally associated with the codingsequence. The signal peptide-coding region may be obtained from aglucoamylase or an amylase gene from an Aspergillus species, a lipase orproteinase gene from a Rhizomucor species, the gene for the alpha-factorfrom Saccharomyces cerevisiae, an amylase or a protease gene from aBacillus species, or the calf preprochymosin gene. However, any signalpeptide-coding region capable of directing the expressed protein intothe secretory pathway of a host cell of choice may be used in thepresent invention.

Fungus Signal Peptide Sequences

An effective signal peptide coding region for filamentous fungal hostcells is the signal peptide coding region obtained from Aspergillusoryzae TAKA amylase gene, Aspergillus niger neutral amylase gene, theRhizomucor miehei aspartic proteinase gene, the Humicola lanuginosacellulase gene, or the Rhizomucor miehei lipase gene.

Yeast Signal Peptide Sequences

Useful signal peptides for yeast host cells are obtained from the genesfor Saccharomyces cerevisiae alpha-factor and Saccharomyces cerevisiaeinvertase. Other useful signal peptide coding regions are described byRomanos et al., 1992, Yeast 8:423-488.

Propeptide Sequences

The DNA construct of the invention may also comprise a propeptide codingregion, which codes for an amino acid sequence positioned at the aminoterminus of a polypeptide. The resultant polypeptide is known as aproenzyme or propolypeptide (or a zymogen in some cases). Apropolypeptide is generally inactive and can be converted to matureactive polypeptide by catalytic or autocatalytic cleavage of thepropeptide from the propolypeptide. The propeptide coding region may beobtained from the Bacillus subtilis alkaline protease gene (aprE), theBacillus subtilis neutral protease gene (nprT), the Saccharomycescerevisiae alpha-factor gene, or the Myceliophthora thermophilum laccasegene (WO 95/33836).

Other Control Sequences

The DNA construct of the present invention may also comprise one or morenucleic acid sequences, which encode one or more factors that areadvantageous in the expression of the polypeptide, e.g., an activator(e.g., a trans-acting factor), a chaperone, and a processing protease.Any factor that is functional in the host cell of choice may be used inthe present invention. The nucleic acids encoding one or more of thesefactors are not necessarily in tandem with the structural gene encodingthe polypeptide.

An activator is a polypeptide, which activates transcription of astructural gene encoding a polypeptide (Kudla et al., 1990, EMBO Journal9:1355-1364; Jarai and Buxton, 1994, Current Genetics 26:2238-244;Verdier, 1990, Yeast 6:271-297). The DNA sequence encoding an activatormay be obtained from the genes encoding Bacillus stearothermophilus NprA(nprA), Saccharomyces cerevisiae heme activator protein 1 (hap1),Saccharomyces cerevisiae galactose metabolizing protein 4 (gal4), andAspergillus nidulans ammonia regulation protein (areA). For furtherexamples, see Verdier, 1990, supra and MacKenzie et al., 1993, Journalof General Microbiology 139:2295-2307.

A chaperone is a protein, which assists another polypeptide in foldingproperly (Hartl et al., 1994, TIBS 19:20-25; Bergeron et al., 1994, TIBS19:124-128; Demolder et al., 1994, Journal of Biotechnology 32:179-189;Craig, 1993, Science 260:1902-1903; Gething and Sambrook, 1992, Nature355:33-45; Puig and Gilbert, 1994, Journal of Biological Chemistry269:7764-7771; Wang and Tsou, 1993, The FASEB Journal 7:1515-11157;Robinson et al., 1994, Bio/Technology 1:381-384). The nucleic acidsequence encoding a chaperone may be obtained from the genes encodingBacillus subtilis GroE proteins, Aspergillus oryzae protein disulphideisomerase, Saccharomyces cerevisiae calnexin, Saccharomyces cerevisiaeBiP/GRP78, and Saccharomyces cerevisiae Hsp70. For further examples, seeGething and Sambrook et al, 1989, Molecular Cloning, A LaboratoryManual, 2d edition, Cold Spring Harbor, N.Y., and Hartl et al., 1994,TIBS 19:20-25.

A processing protease is a protease that cleaves a propeptide togenerate a mature biochemically active polypeptide (Enderlin andOgrydziak, 1994, Yeast 10:67-79; Fuller et al., 1989, Proceedings of theNational Academy of Sciences USA 86:1434-1438; Julius et al., 1984, Cell37:1075-1089; Julius et al., 1983, Cell 32:839-852). The nucleic acidsequence encoding a processing protease may be obtained from the genesencoding Aspergillus niger Kex2, Saccharomyces cerevisiaedipeptidylaminopeptidase, Saccharomyces cerevisiae Kex2, and Yarrowialipolytica dibasic processing endoprotease (xpr6).

Regulatory Sequences

The DNA construct of the invention may also comprise regulatorysequences, which allow the regulation of the expression of thepolypeptide relative to the growth of the host cell. Examples ofregulatory systems are those which cause the expression of the gene tobe turned on or off in response to a chemical or physical stimulus,including the presence of a regulatory compound. In yeast, the ADH2system or GAL1 system may be used. In filamentous fungi, the TAKAalpha-amylase promoter, Aspergillus niger glucoamylase promoter, and theAspergillus oryzae glucoamylase promoter may be used as regulatorysequences. Other examples of regulatory sequences are those, which allowfor gene amplification. In eukaryotic systems, these include thedihydrofolate reductase gene, which is amplified in the presence ofmethotrexate, and the metallothionein genes, which are amplified withheavy metals. In these cases, the structural gene encoding a polypeptidewould be placed in tandem with the regulatory sequence.

Expression Vectors

The present invention also relates to recombinant expression vectorscomprising a DNA sequence or DNA construct of the invention forregulating transcription, and transcriptional and translational stopsignals. The various DNA and control sequences described above may bejoined together to produce a recombinant expression vector, which mayinclude one or more convenient restriction sites to allow for insertionor substitution of the nucleic acid sequence encoding the polypeptide atsuch sites. Alternatively, the structural gene encoding a polypeptidemay be expressed by inserting the DNA sequence of the invention or a DNAconstruct into an appropriate vector for expression. In creating theexpression vector, the polypeptide coding sequence is located in thevector so that the coding sequence is operably linked with theappropriate control sequences for expression, and possibly secretion.

The recombinant expression vector may be any vector (e.g., a plasmid orvirus), which can be conveniently subjected to recombinant DNAprocedures and can bring about the expression of the structural geneencoding the polypeptide. The choice of the vector will typically dependon the compatibility of the vector with the eukaryotic host cell intowhich the vector is to be introduced. The vectors may be linear orclosed circular plasmids. The vector may be an autonomously replicatingvector, i.e., a vector which exists as an extrachromosomal entity, thereplication of which is independent of chromosomal replication, e.g., aplasmid, an extrachromosomal element, a minichromosome, a cosmid or anartificial chromosome. The vector may contain any means for assuringself-replication. Alternatively, the vector may be one which, whenintroduced into the host cell, is integrated into the genome andreplicated together with the chromosome(s) into which it has beenintegrated. The vector system may be a single vector or plasmid or twoor more vectors or plasmids which together contain the total DNA to beintroduced into the genome of the host cell, or a transposon.

The vectors of the present invention preferably contain one or moreselectable markers, which permit easy selection of transformed cells. Aselectable marker is a gene the product of which provides for biocide orviral resistance, resistance to heavy metals, prototrophy to auxotrophs,and the like. Examples of bacterial selectable markers are the dal genesfrom Bacillus subtilis or Bacillus licheniformis, or markers whichconfer antibiotic resistance such as ampicillin, kanamycin,chloramphenicol or tetracycline resistance. A frequently used mammalianmarker is the dihydrofolate reductase gene. Suitable markers for yeasthost cells are ADE2, HIS3, LEU2, LYS2, MET3, TRP1, and URA3. Aselectable marker for use in a filamentous fungal host cell may beselected from the group including, but not limited to, amdS(acetamidase), argB (ornithine carbamoyltransferase), bar(phosphinothricin acetyltransferase), hygB (hygromycinphosphotransferase), niaD (nitrate reductase), pyrG(orotidine-5′-phosphate decarboxylase), sC (sulfate adenyltransferase),trpC (anthranilate synthase), and glufosinate resistance markers, aswell as equivalents from other species. Preferred for use in anAspergillus cell are the amdS and pyrG markers of Aspergillus nidulansor Aspergillus oryzae and the bar marker of Streptomyces hygroscopicus.Furthermore, selection may be accomplished by co-transformation, e.g.,as described in WO 91/17243, where the selectable marker is on aseparate vector.

The vectors of the present invention preferably contain an element(s)that permits stable integration of the vector into the host cell genomeor autonomous replication of the vector in the cell independent of thegenome of the cell.

The vectors of the present invention may be integrated into the hostcell genome when introduced into a host cell. For integration, thevector may rely on the nucleic acid sequence encoding the polypeptide orany other element of the vector for stable integration of the vectorinto the genome by homologous or none homologous recombination.Alternatively, the vector may contain additional nucleic acid sequencesfor directing integration by homologous recombination into the genome ofthe host cell. The additional nucleic acid sequences enable the vectorto be integrated into the host cell genome at a precise location(s) inthe chromosome(s). To increase the likelihood of integration at aprecise location, the integrational elements should preferably contain asufficient number of nucleic acids, such as 100 to 1,500 base pairs,preferably 400 to 1,500 base pairs, and most preferably 800 to 1,500base pairs, which are highly homologous with the corresponding targetsequence to enhance the probability of homologous recombination. Theintegrational elements may be any sequence that is homologous with thetarget sequence in the genome of the host cell. Furthermore, theintegrational elements may be non-encoding or encoding nucleic acidsequences. On the other hand, the vector may be integrated into thegenome of the host cell by non-homologous recombination. These nucleicacid sequences may be any sequence that is homologous with a targetsequence in the genome of the host cell, and, furthermore, may benon-encoding or encoding sequences.

For autonomous replication, the vector may further comprise an origin ofreplication enabling the vector to replicate autonomously in the hostcell in question. Examples of bacterial origins of replication are theorigins of replication of plasmids pBR322, pUC19, pACYC177, pACYC184,pUB110, pE194, pTA1060, and pAMβ1. Examples of origin of replicationsfor use in a yeast host cell are the 2 micron origin of replication, thecombination of CEN6 and ARS4, and the combination of CEN3 and ARS1. Theorigin of replication may be one having a mutation which makes itsfunctioning temperature-sensitive in the host cell (see, e.g., Ehrlich,1978, Proceedings of the National Academy of Sciences USA 75:1433).

The episomal replicating AMA1 plasmid vector disclosed in WO 00/24883may also be used.

More than one copy of a structural gene encoding a polypeptide may beinserted into the host cell to amplify expression of the structuralgene. Stable amplification of the structural gene can be obtained byintegrating at least one additional copy of the sequence into the hostcell genome using methods well known in the art and selecting fortransformants.

The procedures used to ligate the elements described above to constructthe recombinant expression vectors of the present invention are wellknown to one skilled in the art (see, e.g., Sambrook et al, 1989,Molecular Cloning, A Laboratory Manual, 2d edition, Cold Spring Harbor,N.Y.).

Eukaryote Host Cells

The invention also relates to eukaryotic host cell comprising a DNAsequence of the invention for regulating transcription or a DNAconstruct of the invention or an expression vector of the invention. Theeukaryotic host cell of the invention comprises a structural geneencoding a polypeptide. The term “host cell” encompasses any progeny ofa parent cell, which is not identical to the parent cell due tomutations that occur during replication. The cell is preferablytransformed with a vector comprising a DNA sequence for regulatingtranscription of the invention operably linked to a structural genefollowed, in particular by integration of the vector into the hostchromosome.

The host cell is a eukaryote, such as a mammalian cell, an insect cell,a plant cell or a fungal cell. Useful mammalian cells include Chinesehamster ovary (CHO) cells, HeLa cells, baby hamster kidney (BHK) cells,COS cells, or any number of other immortalized cell lines available,e.g., from the American Type Culture Collection.

In a preferred embodiment, the host cell is a fungal cell. “Fungi” asused herein includes the phyla Ascomycota, Basidiomycota,Chytridiomycota, and Zygomycota (as defined by Hawksworth et al., In,Ainsworth and Bisby's Dictionary of The Fungi, 8th edition, 1995, CABInternational, University Press, Cambridge, UK) as well as the Oomycota(as cited in Hawksworth et al., 1995, supra, page 171) and allmitosporic fungi (Hawksworth et al., 1995, supra). Representative groupsof Ascomycota include, e.g., Neurospora, Eupenicillium (=Penicillium),Emericella (=Aspergillus), Eurotium (=Aspergillus), and the true yeastslisted above. Examples of Basidiomycota include mushrooms, rusts, andsmuts. Representative groups of Chytridiomycota include, e.g.,Allomyces, Blastocladiella, Coelomomyces, and aquatic fungi.Representative groups of Oomycota include, e.g., Saprolegniomycetousaquatic fungi (water molds) such as Achlya. Examples of mitosporic fungiinclude Aspergillus, Penicillium, Candida, and Alternaria.

Representative groups of Zygomycota include, e.g., Rhizopus and Mucor.

In a preferred embodiment, the fungal host cell is a yeast cell. “Yeast”as used herein includes ascosporogenous yeast (Endomycetales),basidiosporogenous yeast, and yeast belonging to the Fungi Imperfecti(Blastomycetes). The ascosporogenous yeasts are divided into thefamilies Spermophthoraceae and Saccharomycetaceae. The latter iscomprised of four subfamilies, Schizosaccharomycoideae (e.g., genusSchizosaccharomyces), Nadsonioideae, Lipomycoideae, andSaccharomycoideae (e.g., genera Pichia, Kluyveromyces andSaccharomyces). The basidiosporogenous yeasts include the generaLeucosporidim, Rhodosporidium, Sporidiobolus, Filobasidium, andFilobasidiella. Yeast belonging to the Fungi Imperfecti are divided intotwo families, Sporobolomycetaceae (e.g., genera Sorobolomyces andBullera) and Cryptococcaceae (e.g., genus Candida). Since theclassification of yeast may change in the future, for the purposes ofthis invention, yeast shall be defined as described in Biology andActivities of Yeast (Skinner, F. A., Passmore, S. M., and Davenport, R.R., eds, Soc. App. Bacteriol. Symposium Series No. 9, 1980. The biologyof yeast and manipulation of yeast genetics are well known in the art(see, e.g., Biochemistry and Genetics of Yeast, Bacil, M., Horecker, B.J., and Stopani, A. O. M., editors, 2nd edition, 1987; The Yeasts, Rose,A. H., and Harrison, J. S., editors, 2nd edition, 1987; and TheMolecular Biology of the Yeast Saccharomyces, Strathern et al., editors,1981).

In a more preferred embodiment, the yeast host cell is a cell of aspecies of Candida, Kluyveromyces, Saccharomyces, Schizosaccharomyces,Pichia, or Yarrowia. In a most preferred embodiment, the yeast host cellis a Saccharomyces carlsbergensis, Saccharomyces cerevisiae,Saccharomyces diastaticus, Saccharomyces douglasii, Saccharomyceskluyveri, Saccharomyces norbensis or Saccharomyces oviformis cell. Inanother most preferred embodiment, the yeast host cell is aKluyveromyces lactis cell. In another most preferred embodiment, theyeast host cell is a Yarrowia lipolytica cell.

In a preferred embodiment, the fungal host cell is a filamentous fungalcell. “Filamentous fungi” include all filamentous forms of thesubdivision Eumycota and Oomycota (as defined by Hawksworth et al., In,Ainsworth and Bisby's Dictionary of The Fungi, 8th edition, 1995, CABInternational, University Press, Cambridge, UK. The filamentous fungiare characterized by a vegetative mycelium composed of chitin,cellulose, glucan, chitosan, mannan, and other complex polysaccharides.Vegetative growth is by hyphal elongation and carbon catabolism isobligately aerobic. In contrast, vegetative growth by yeasts such asSaccharomyces cerevisiae is by budding of a unicellular thallus andcarbon catabolism may be fermentative. In a more preferred embodiment,the filamentous fungal host cell is a cell of a species of, but notlimited to, Acremonium, Aspergillus, Fusarium, Humicola, Mucor,Myceliophthora, Neurospora, Penicillium, Thielavia, Tolypocladium, andTrichoderma or a teleomorph or synonym thereof. In an even morepreferred embodiment, the filamentous fungal host cell is an Aspergilluscell. In another even more preferred embodiment, the filamentous fungalhost cell is an Acremonium cell. In another even more preferredembodiment, the filamentous fungal host cell is a Fusarium cell. Inanother even more preferred embodiment, the filamentous fungal host cellis a Humicola cell. In another even more preferred embodiment, thefilamentous fungal host cell is a Mucor cell. In another even morepreferred embodiment, the filamentous fungal host cell is aMyceliophthora cell. In another even more preferred embodiment, thefilamentous fungal host cell is a Neurospora cell. In another even morepreferred embodiment, the filamentous fungal host cell is a Penicilliumcell. In another even more preferred embodiment, the filamentous fungalhost cell is a Thielavia cell. In another even more preferredembodiment, the filamentous fungal host cell is a Tolypocladium cell. Inanother even more preferred embodiment, the filamentous fungal host cellis a Trichoderma cell. In a most preferred embodiment, the filamentousfungal host cell is an Aspergillus awamori, Aspergillus foetidus,Aspergillus japonicus, Aspergillus niger or Aspergillus oryzae cell. Inanother most preferred embodiment, the filamentous fungal host cell is aFusarium cell of the section Discolor (also known as the sectionFusarium). For example, the filamentous fungal parent cell may be aFusarium bactridioides, Fusarium cerealis, Fusarium crookwellense,Fusarium culmorum, Fusarium graminearum, Fusarium graminum, Fusariumheterosporum, Fusarium negundi, Fusarium reticulatum, Fusarium roseum,Fusarium sambucinum, Fusarium sarcochroum, Fusarium sulphureum, orFusarium trichothecioides cell. In another preferred embodiment, thefilamentous fungal parent cell is a Fusarium strain of the sectionElegans, e.g., Fusarium oxysporum. In another most preferred embodiment,the filamentous fungal host cell is a Humicola insolens or Humicolalanuginosa cell. In another most preferred embodiment, the filamentousfungal host cell is a Mucor miehei cell. In another most preferredembodiment, the filamentous fungal host cell is a Myceliophthorathermophilum cell. In another most preferred embodiment, the filamentousfungal host cell is a Neurospora crassa cell. In another most preferredembodiment, the filamentous fungal host cell is a Penicilliumpurpurogenum cell. In another most preferred embodiment, the filamentousfungal host cell is a Thielavia terrestris cell. In another mostpreferred embodiment, the Trichoderma cell is a Trichoderma harzianum,Trichoderma koningii, Trichoderma longibrachiatum, Trichoderma reesei orTrichoderma viride cell.

The host cell of the invention may be a protease transcription activatorless strain, in particular a prtT gene deleted strain. In particular thehost cell may be an Aspergillus, such as A. niger or A. oryzae strain asdescribed in WO 00/20596.

Transformation of Eukaryote Host Cells

Fungal cells may be transformed by a process involving protoplastformation, transformation of the protoplasts, and regeneration of thecell wall in a manner known per se. Suitable procedures fortransformation of Aspergillus host cells are described in EP 238 023 andYelton et al., 1984, Proceedings of the National Academy of Sciences USA81:1470-1474. A suitable method of transforming Fusarium species isdescribed by Malardier et al., 1989, Gene 78:147-156 or in copendingU.S. Ser. No. 08/269,449. Yeast may be transformed using the proceduresdescribed by Becker and Guarente, In Abelson, J. N. and Simon, M. I.,editors, Guide to Yeast Genetics and Molecular Biology, Methods inEnzymology, Volume 194, pp 182-187, Academic Press, Inc., New York; Itoet al., 1983, Journal of Bacteriology 153:163; and Hinnen et al., 1978,Proceedings of the National Academy of Sciences USA 75:1920. Mammaliancells may be transformed by direct uptake using the calcium phosphateprecipitation method of Graham and Van der Eb (1978, Virology 52:546).

Cultivation of Host Cell

The methods used for cultivation of microbial or plant host cells areknown in the art.

METHODS OF THE INVENTION

In an aspect the invention relates to a method of producing apolypeptide, comprising:

(a) cultivating a host cell of the invention, wherein the host cellharbours a structural gene under control of a DNA sequence of theinvention, in a nutrient medium suitable for production of thepolypeptide; and

(b) recovering the polypeptide from the nutrient medium.

The host cell may be any of the above mentioned. The DNA sequence of theinvention may be located upstream to a structural gene encoding apolypeptide, which may be native or foreign to the host cell.

The invention also relates to a method of increasing the transcriptionand/or expression levels of a eukaryotic host cell comprisingintroducing one or more RNA polymerase binding sites upstream to aparent RNA polymerase binding site or promoter.

The term “parent” RNA polymerase binding site or promoter means the siteor promoter present in the host cell before modification. The method canbe used to provide host cell for both homologous and heterologousproduction. In a homologous host the promoter may be replaced with a DNAsequence of the invention.

In an embodiment the DNA sequence of the invention for regulatingtranscription is introduced upstream to the structural gene or theparent RNA polymerase binding site or promoter is replaced with the DNAsequence of the invention. In an embodiment the introduced RNApolymerase binding sites consists of one or more repetitive DNAsequences which is capable of binding RNA polymerase.

In an embodiment RNA polymerase binding sites are tandem sites.

Materials & Methods

Chemicals used as buffers and substrates were commercial products of atleast reagent grade.

Media and Solutions

MY25 medium at pH 6.5 was composed per liter (L) of 25 g of maltose, 2.0g of MgSO₄.7H₂O, 10 g of KH₂PO₄, 2.0 g of citric acid, 10 g of yeastextract, 2.0 g of K₂SO₄, 2.0 g of urea, 1.0 mL of CaCl₂.2H₂O (100 g/lstock solution), and 0.5 mL of trace metals solution. MY25 microtitermedium was diluted 1:100 with 490 mL glass distilled water and 500 mL2×MY Salts. Cultures were grown at 30° C.

2×MY Salts pH 6.5 solutions was composed per liter of 4 g of MgSO₄.7H₂O,4 g of K₂SO₄, 20 g of KH₂PO₄, 4 g of citric acid, 1 mL of trace metalssolution, and 2 mL of CaCl₂.2H₂O (100 g/l stock solution).

Minimal medium transformation plates were composed per liter of 6 g ofNaNO₃, 0.52 g of KCl, 1.52 g of KH₂PO₄, 1 mL of trace metals solution,10 g of glucose, 500 mg of MgSO₄.7H₂O, 342.3 g of sucrose, and 20 g ofNoble agar (pH 6.5). Minimal medium transfer plates (pH 6.5) werecomposed per liter of 6 g of NaNO₃, 0.52 g of KCl, 1.52 g of KH₂PO₄, 1mL of trace elements, 1 g of glucose, 500 mg of MgSO₄.7H₂O, and 20 gNoble agar.

Minimal Medium was composed per liter of 6 g of NaNO₃, 0.52 g of KCl,1.52 g of KH₂PO₄, 1 mL trace metals, 10 g of glucose, 500 mg ofMgSO₄.7H₂O, 342.3 g of sucrose, and 20 g of Noble agar at pH 6.5.Transfer plates were the same as above, but omitting the sucrose.

The trace metals solution (1000×) was composed per liter of 22 g ofZnSO₄.7H₂O, 11 g of H₃BO₃, 5 g of MnCl₂.4H₂O, 5 g of FeSO₄.7H₂O, 1.6 gof CoCl₂.5H₂O, 1.6 g of (NH₄)₆Mo₇O₂₄, and 50 g of Na₄EDTA.

Chlorate plate was composed of Minimal Medium supplemented 470 mMchlorate and 10 mM glutamate as sole nitrogen source.

YPM medium was composed per liter of 5 g yeast extract, 10 g Bactopeptone, and 2 g Maltose.

AMG trace-element solution is composed of 2.5 g of CuSO₄.5H₂O, 6.8 g ofZnCl₂, 0.24 g of NiCl₂.6H₂O, 13.9 g of FeSO₄.7H₂O, 13.6 g of MnSO₄.5H₂O,and 3.0 g of Citric acid monohydrate (Wako No. 035-03495), water to 1liter.

GO-50 is composed of 50 g of glucose, 2 g of KH₂PO₄, 2 g of MgSO₄.7H₂O,3 g of K₂SO₄, 2 g of citric acid monohydrate (Wako No. 035-03495), 50 gof oxalic acid.2H₂O, 0.5 ml of AMG trace element solution and 50 g ofoxalic acid.2H₂O (pH 4.5), water to 1 liter. Before use 3 ml of 10% Ureais added.

Cove-N plates are composed of 342.3 g of sucrose, 3 g of NaNO₃, 20 ml ofCove salt solution, and 30 g of noble agar, water to 1 liter.

Cove salt solution is composed of 26 g of KCl, 26 g of MgSO₄.7H₂O, 76 gof KH₂PO₄ and 50 ml Cove trace-element J solution, water to 1 liter.

Cove top aqarose is composed of 342.3 g of Sucrose, 20 ml of Cove saltsolution, 3 g of NaNO₃ and 10 g of low melt agarose, water to 1 liter.

Cove trace-element J solution is composed of 0.04 g NaB₄O₇.10H₂O, 0.4 gof CuSO₄.5H₂O, 1.2 g of FeSO₄.7H₂O, 1.0 g of MnSO₄.H₂O, 0.8 g ofNa₂MoO₂.2H₂O, and 10.0 g of ZnSO₄.7H₂O, water to 1 liter.

Cove-N2 plates are composed of 30 g of sucrose, 20 ml of Cove saltsolution, 3 g of NaNO₃ and 30 g of noble agar, water to 1 liter.

MLC is composed of 50 g of soybean powder, 40 g of glucose, and 4 gcitric acid monohydrate (Wako No. 035-03495), water to 1 liter (pH 5.0).

STC buffer is composed of 0.8 M of sorbitol, 25 mM of Tris (pH 8), and25 mM of CaCl₂, water to 1 liter.

STPC buffer is composed of 40% PEG4000 in STC buffer.

YPG medium is composed of 4 g of yeast extract, 1 g of KH₂PO₄, 0.5 g ofMgSO₄.7H₂O and 15 g of Glucose, water to 1 liter (pH 6.0).

Strains

JaL228: The construction of this strain is described in patent WO98/12300.

JaL250: The construction of this strain is described in Example 7.

JaL294: The construction of this strain is described in Example 8.

MBin119: Aspergillus niger expression host MBin119 is a straingenetically modified to disrupt expression of glucoamylase, acid-stablealpha-amylase, neutral amylase I and II, pyrG and alpha-1,6transglucosidase activities.

Plasmids

pNA2: The construction is described in patent WO 89/01969.

p960 The construction is described in patent EP 0305,206 A1.

pJeRS4: The construction is described in U.S. Pat. No. 5,861,280

pIC19H: The construction is described in Marsh et al, 1984, Gene32:481-485.

pUC19: The construction is described in Vieira et al, 1982, Gene19:259-268

pSTA14: are described in Unkles et al., 1989, Molecular General Genetics218: 99-104

pJaL211: The construction is described in example 1.

pJaL240: The construction is described in example 2.

pToC108: The construction is described in example 3 pJaL410: Theconstruction is described in example 3.

pJaL420: The construction is described in example 3.

pJaL423: The construction is described in example 3.

pJaL475: The construction is described in example 3.

pJaL479: The construction is described in example 3.

pJaL485: The construction is described in example 3.

pJaL535: The construction is described in example 4.

pJaL676: The construction is described in example 5.

pToC432: The construction is described in example 6.

pJaL419: The construction is described in example 8.

pJaL448: The construction is described in example 8.

pJaL700: The construction is described in example 9.

pJaL701: The construction is described in example 10.

pJaL724: The construction is described in example 11.

pJaL729: The construction is described in example 12.

pJaL719: The construction is described in Example 16.

pJaL721: The construction is described in Example 17.

The plasmid pCaHj483 comprises A. niger Neutral-amylase 2 promoter(NA2), the Aspergillus nidulans TPI leader sequences, the Aspergillusniger glucoamylase terminator and the A. nidulans amdS gene.

Transformation of Aspergillus niger

Transformation of Aspergillus niger can be achieved with generalprotoplasts methods. The preferred procedure for the invention isdescribed below.

The host strain is propagated in 100 ml of non-selective YPG medium at32° C. for 16 hrs on a rotary shaker at 120 rpm. Cells are collected byfiltering, washed with 0.6 M KCl and resuspended in 20 ml of 0.6 M KClcontaining a commercial beta-glucanase product (GLUCANEX™, NovozymesA/S) at 600 microL/ml. The suspension is incubated at 32° C. at 80 rpmuntil protoplasts are formed, then washed twice with STC buffer. Theprotoplasts are counted with a hematometer and resuspended and adjustedin an 8:2:0.1 solution of STC:STPC:DMSO to a final concentration of2.5×107 protoplasts/ml. About 3 microgram of DNA is added to 100 microLof protoplast suspension, mixed gently and incubated on ice for 20 min.One ml of SPTC is added and the protoplast suspension is incubated for30 min at 37° C. After the addition of 10 ml of 50° C. Cove top agarose,the reaction is poured onto Cove-N agar plates and the plates areincubated at 32° C. for 5 days. As untransformed cells cannot grow onCove-N medium, transformants are easily selected.

EXAMPLES Example 1 Construction of pJaL211

Plasmid pJaL211 was constructed to contain the A. niger neutral amylase2 (NA2) promoter.

The 923 bp HindIII-BamHI fragment from pNA2 was ligated to the 4278 bpHindIII-BamHI fragment from p960, resulting in pJaL211.

Example 2 Construction of pJaL240

Plasmid pJaL240 was constructed to contain a 611 bp fragment of the A.niger neutral amylase 2 (NA2) promoter.

The 611 bp EcoRI-BamHI fragment from pJaL211 was ligated to the 2690 bpEcoRI-BamHI fragment from pIC19H, resulting in pJaL240.

Example 3 Construction of pJaL485

Plasmid pJaL485 was constructed to contain the truncated niaD gene andan expression cassette where the Humicola lanuginosa lipase gene wassandwiched between the NA2 promoter and the Aspergillus niger AMGterminator.

Plasmid pSTA14 encoding the Aspergillus oryzae niaD gene (Unkles et al.,1989, Molecular General Genetics 218: 99-104) was digested with HindIIIand the 5136 bp fragment was purified and cloned into pUC19 digestedwith HindIII to yield plasmid pToC108. Plasmid pToC108 was digested withBglII-SalI and the 3700 bp fragment was purified and cloned into pUC19digested with BglII-SalI to yield plasmid pJaL410. This plasmid isencoding a truncated niaD gene wherein the 85 N-terminal amino acidshave been removed.

Plasmid pJaL410 was digested with SacI-PstI and treated with Klenow anddNTP's and the 6018 bp fragment was purified and religated to yieldplasmid pJaL420. The BamHI site in pJaL420 was removed by making asilent mutation by using the Chameleon Double-Stranded Site-DirectedMutagenesis Kit (Stratagene Cloning Systems, La Jolla, Calif.) accordingto the manufacturer's instructions giving plasmid pJaL423. The BamHIsite was destroyed by changing the T in the BamHI site to a C using thefollowing primer:

(SEQ ID NO: 2) 5′-GGAACGATGGACCCGGAAGGTTTAAAAGC-3′

Sequencing around the destroyed BamHI site revealed that furtherdownstream there was some unexpected changes, which resulted in a frameshift in the niaD gene and the creation of a SmaI site. To repair thisframe shift the 291 bp Accl-DraI fragment in pJaL423 was exchanged withthe corresponding fragment from pJaL420 to give pJaL475.

The 3381 bp HindIII fragment from pJaL475 encoding the truncated niaDgene was cloned into the HindIII site of plasmid pJaL211, resulting inplasmid pJaL479. The HindIII site at position 2 was destroyed by partialdigestion with HindIII followed by treatment with Klenow and dNTP's. The8586 bp fragment was purified and religated to yield plasmid pJaL485.

Example 4 Construction of pJaL535

Plasmid pJaL535 was constructed to contain the truncated niaD gene andan expression cassette where the Humicola lanuginosa lipase gene wassandwiched between the NA2 promoter (shown in position 7-510 of SEQ IDNO: 1) and the Aspergillus niger AMG terminator.

The 644 bp HindIII-BamHI fragment from pJaL240 was ligated to the 7663bp HindIII-BamHI fragment from pJaL485, resulting in pJaL535.

Example 5 Construction of pJaL676

Plasmid pJaL676 is a derivative of pJaL535 where the NA2 promoter shownin position 7-510 of SEQ ID NO: 1 has been modified in several runs ofsite directed mutagenesis by a simple PCR approach.

Nucleotides 135-145 were altered from SEQ ID NO: 3 to SEQ ID NO: 4 usingthe mutagenic primer in SEQ ID NO: 5.

Nucleotides 407-422 were altered from SEQ ID NO: 6 to SEQ ID NO: 7 usingthe mutagenic primer in SEQ ID NO: 8.

Nucleotides 424-437 were altered from SEQ ID NO: 9 to SEQ ID NO: 10using the mutagenic primer in SEQ ID NO: 11.

Nucleotides 529-617 were altered from SEQ ID NO: 12 to SEQ ID NO: 13using the mutagenic primer in SEQ ID NO: 14.

The resulting plasmid was termed pJaL676.

Example 6 Construction of pToC432

Plasmid pToC432 is a derivative of pJaL535 where the NA2 promoter shownin position 7-510 of SEQ ID NO: 1 has been modified in several runs ofsite directed mutagenises by a simple PCR approach.

Nucleotides 135-145 were altered from SEQ ID NO: 3 to SEQ ID NO: 4 usingthe mutagenic primer in SEQ ID NO: 5.

Nucleotides 407-422 were altered from SEQ ID NO: 6 to SEQ ID NO: 7 usingthe mutagenic primer in SEQ ID NO: 8.

Nucleotides 529-617 were altered from SEQ ID NO: 12 to SEQ ID NO: 13using the mutagenic primer in SEQ ID NO: 14.

The resulting plasmid was termed pToC432.

Example 7 Isolation of a pyrG Minus Aspergillus oryzae JaL250

The A. oryzae strain JaL228, described in WO 98/12300, was screened forresistance to 5-fluoro-orotic acid to identify spontaneous pyrG mutants.One strain, named JaL250, was identified as being pyrG minus. The mutantis uridine dependent, therefore it can be transformed with the wild typepyrG gene and transformants selected by the ability to grow in theabsence of uridine.

Example 8 Construction of Aspergillus oryzae JaL294

For construction of a defined Aspergillus oryzae niaD mutant areplacement plasmid pJaL448 was constructed where the C-terminal part ofthe niaD gene was replaced by the Aspergillus oryzae pyrG gene.

Plasmid pJaL410 (construction described in Example 3) was digested withKpnI and the 4307 bp fragment was purified and religated to yieldplasmid pJaL419. Plasmid pJeRS4 encoding the Aspergillus oryzae pyrGgene was digested with KpnI and the 1515 bp fragment was purified andligated with pJaL419 digested with KpnI to yield pJaL448.

Plasmid pJaL448 is a double cross-over plasmid where the Aspergillusoryzae pyrG gene (1515 bp KpnI fragment from pJeRS4) is flanked by a 782bp BglII-KpnI fragment encoding amino acid 85 to 276 of the niaD proteinand by a 841 bp KpnI-HindIII fragment containing the niaD terminator.

Protoplasts preparation of Aspergillus oryzae JaL250: The Aspergillusoryzae JaL250 was grown in 100 mL of YEG medium at 34° C. for 16-18hours with agitation at 160 rpm. The mycelia were recovered byfiltration through a 0.2 micro m filter until approximately 10 mLremained on the filter, washed with approximately 20 ml of 1 MMgSO₄.7H₂O (0.2 micro m filtered), and then collected with a sterileloop and placed in a 125 mL Ehrlenmeyer flask. The mycelia were thenresuspended with 75 mg of NOVOZYM 234™ (from Novozymes A/S, Bagsvaerd,Denmark) in 15 mL of 1 M MgSO₄.7H₂O. The suspension was incubated at 37°C. with gentle agitation at 50 rpm for approximately one hour togenerate protoplasts.

The contents of the 125 mL Ehrlenmeyer flask was then filtered throughsterile Miracloth into a 30 mL Corex centrifuge tube, overlaid with 6 mLof 0.6 M sorbitol-100 mM Tris pH 7.0, and centrifuged at 3500×g for 15minutes in a swinging bucket rotor to recover the protoplasts. Theprotoplasts were recovered from the buffer interface with a Pasteurpipet. The protoplasts were then washed with two volumes of STC (1.2 Msorbitol-10 mM Tris-10 mM CaCl₂.2H₂O pH 7.5) and centrifuged at 3500×gfor 5 minutes. The protoplasts were washed two times in 10 mL of STC andcentrifuged as before. The protoplasts were resuspended in STC to afinal concentration of 1.7×10⁷ protoplasts per mL. pJaL448 waslinearized with XhoI and transformed into protoplasts of Aspergillusoryzae JaL250. Transformation of Aspergillus oryzae JaL250 for chlorateresistance selection was conducted with protoplasts at a concentrationof 1.7×10⁷ protoplasts per mL. Ten micro g of linearized pJaL448 wereadded to 100 microL of protoplasts. A volume of 250 microL of PEGsolution (60% PEG 4000-10 mM CaCl₂) was then added and the mixture wasplaced at 37° C. for 30 minutes. Four mL STC was then added and themixture was plated onto Minimal media plates selecting for chlorateresistance. The plates were incubated 5-7 days at 37° C. Chlorateresistance transformants (9 out 45) were isolated and further purifiedon chlorate-containing minimal medium with glutamate as the sole sourceof nitrogen. The ability of these 9 mutants to grow on nitrate andnitrite as sole nitrogen source was assessed. Three had a phenotypeindicative of nitrate reductase structural mutants (niaD), i.e., theyfailed to grow with nitrate but grew on nitrite as sole nitrogen source.

Southern analysis of BamHI-, KpnI-, and HindIII-digested genomic DNAfrom the three mutant strains, probed with either the 2 kb KpnI fragmentor with the 3.7 kb HindIII fragment from pJaL410, demonstrated that onlyone of the transformants, designated Aspergillus oryzae JaL294, has theexpected gene replacement at the niaD locus.

Example 9 Construction of pJaL700

Plasmid pJaL700 is a derivate of pToC432 where part of the NA2 promoterfrom position 7 to 510 has been duplicated. By PCR with primers SEQ IDNO: 15 and SEQ ID NO: 16 a 534 bp DNA fragment was amplified frompToC432, purified, and digested with the restriction endonucleases EcoRIand HindIII, resulting in a 516 bp DNA fragment. The 516 bp DNA fragmentwas ligated together with the 8283 bp HindIII-EcoRI DNA fragment frompJaL676, resulting in plasmid pJaL700 (FIG. 1).

Example 10 Construction of pJaL701

Plasmid pJaL701 is a derivate of pToC432 where part of the NA2 promoterfrom position 7 to 510 has been duplicated. By PCR with primers SEQ IDNO: 15 and SEQ ID NO: 17 a 574 bp DNA fragment was amplified frompToC432, purified, and digested with the restriction endonucleases EcoRIand HindIII, resulting in a 556 bp DNA fragment. The 556 bp DNA fragmentwas ligated together with the 8283 bp HindIII-EcoRI DNA fragment frompJaL676, resulting in plasmid pJaL701 (FIG. 2).

Example 11 Construction of pJaL724

Plasmid pJaL724 is a derivate of pJaL676 where part of the NA2 promoterfrom position 7 to 510 has been duplicated. By PCR with primers SEQ IDNO: 15 and SEQ ID NO: 16 a 538 bp DNA fragment was amplified frompJaL676, purified, and digested with the restriction endonucleases EcoRIand HindIII, resulting in a 514 bp DNA fragment. The 514 bp DNA fragmentwas ligated together with the 8283 bp HindIII-EcoRI DNA fragment frompJaL676, resulting in plasmid pJaL724.

Example 12 Construction of pJaL729

Plasmid pJaL729 is a derivate of pJaL676 where part of the NA2 promoterfrom position 7 to 510 has been triplicated. By PCR with primers SEQ IDNO: 15 and SEQ ID NO: 16 a 538 bp DNA fragment was amplified frompJaL676, purified, digested with the restriction endonucleases EcoRI,and was blunt ended by treatment with Klenow polymerase and dNTP's,resulting in a 520 bp DNA fragment. The 520 bp DNA fragment was ligatedtogether with the 8797 bp HindIII DNA fragment from pJaL724, resultingin plasmid pJaL729.

Example 13 Transformation of Aspergillus oryzae JaL294

Aspergillus oryzae JaL294 was grown in 100 mL of YEG medium at 34° C.for 16-18 hours with agitation at 160 rpm. The mycelia were recovered byfiltration through a 0.2 micro m filter until approximately 10 mLremained on the filter, washed with approximately 20 mL of 1 MMgSO₄.7H₂O (0.2 micro m filtered), and then collected with a sterileloop and placed in a 125 mL Ehrlenmeyer flask. The mycelia were thenresuspended with 75 mg of NOVOZYM 234™ (Novozymes A/S, Bagsvaerd,Denmark) in 15 mL of 1 M MgSO₄.7H₂O. The suspension was incubated at 37°C. with gentle agitation at 50 rpm for approximately one hour togenerate protoplasts.

The contents of the 125 mL Ehrlenmeyer flask was then filtered throughsterile Miracloth into a 30 mL Corex centrifuge tube, overlaid with 6 mLof 0.6 M sorbitol-100 mM Tris pH 7.0, and centrifuged at 3500×g for 15minutes in a swinging bucket rotor to recover the protoplasts. Theprotoplasts were recovered from the buffer interface with a Pasteurpipet. The protoplasts were then washed with two volumes of STC (1.2 Msorbitol-10 mM Tris-10 mM CaCl₂.2H₂O pH 7.5) and centrifuged at 3500×gfor 5 minutes. The protoplasts were washed two times in 10 mL of STC andcentrifuged as before. The protoplasts were resuspended in STC to afinal concentration of 1.7×10⁷ protoplasts per mL.

Transformation of Aspergillus oryzae JaL294 for niaD selection wasconducted with protoplasts at a concentration of 1.7×10⁷ protoplasts permL. Five micro g of DNA (pToC432, pJaL676, pJaL700, pJaL701, pJaL724, orpJaL729) were added to 100 microL of protoplasts. A volume of 250 microLof PEG solution (60% PEG 4000-10 mM CaCl₂) was then added and themixture was placed at 37° C. for 30 minutes. Four mL STC was then addedand the mixture was plated onto Minimal media plates selecting for niaD.The plates were incubated 5-7 days at 37° C. The transformants werepurified by streaking spores and picking isolated colonies from Minimalmedia plates incubated at 37° C.

Example 14 Characterization of Integration Events in Aspergillus oryzaeJaL294 Transformants

Genomic DNA was isolated from all of the Aspergillus oryzae JaL294transformants according to the following procedure. Each transformantwas grown in 10 mL of YPM medium for 24 hours at 30° C. in a 25 mL testtube (NUNC container). Mycelia were then collected from each culture byfiltration through Whatman filter paper No. 1 (Whatman, SpringfieldMill, England) and transferred to a 1.7 mL centrifuge tube. The myceliapreparations were frozen in liquid nitrogen and dried in a Speed-Vac(Savant Instruments, Inc., Farmingdale, N.Y.) for 1.5 hours. The frozenmycelia preparations were ground to a fine powder with a steriletoothpick. A Qiagen DNeasy Kit (QIAGEN, Inc., Valencia, Calif.) was usedto extract the genomic DNA from the frozen mycelia following themanufacturer's instructions.

The genomic DNA was digested with PstI and then Southern hybridizationwas used to determine whether there was a single copy of the plasmidintegrated into the transformants according to the procedure describedby Sambrook et al., 1989, supra. Additionally, genomic DNA was extractedfrom untransformed Aspergillus oryzae JaL294. Southern blots of thedigests were probed with a 1.8 kb niaD fragment obtained from pToC108.The fragment was labeled with dioxygenin using a Boehringer Mannheim PCRDIG Probe Synthesis Kit (Boehringer Mannheim, Indianapolis, Ind.)according to the manufacturer's instructions. The blot was prehybridizedfor 2 hours and hybridized overnight at 50° C. in DIG Easy Hyb. The blotwas washed and processed as recommended by the manufacturer.

The Southern blot demonstrated that pJaL485 contained a 8.5 kb band anduntransformed Aspergillus oryzae JaL294 contained a 3.8 kb band whenprobed with the niaD fragment. Transformants in which a single copy ofthe plasmid was integrated should contain an 11.7 kb and 3.8 kb bands.Transformants in which multiple copies of the plasmid were integratedshould contain the same 11.7 kb and 3.8 kb bands as well as a third bandof 8.5 kb. Those transformants, which had integrated a single copy ofthe plasmid DNA, were then grown in shake flask and subsequently assayedfor lipase expression.

Example 15 Analysis of Transformants in Shake Flask

The Aspergillus oryzae JaL294 transformants obtained in Example 13 wereassayed for lipase expression. For microtiter assays, MY25 medium wasdiluted 100 fold with 49% glass distilled water and 50% 2×MY Salts pH6.5 solution. A volume of 1.25 mL of 1/100 strength MY25 medium wasadded to the wells of a 24 well cell culture plate. The wells wereinoculated with 10 microL of spores from each transformant, and theplates were incubated at 34° C. with agitation at 100 rpm. Eachtransformant was inoculated into three wells. Untransformed Aspergillusoryzae JaL294 was used to inoculate three wells.

Samples of 100 microL were removed on days 2 and 4 from each well of the24 well cell culture plates. Each sample was diluted with 200 microL of100 mM alpha olefin sulfonate (AOS) detergent in 4 mM CaCl₂-100 mM MOPSpH 7.5 (MC buffer) and 20 microL aliquots were dispensed to wells in96-well plates followed by 200 microL of diluted substrate. The lipaseassay substrate was prepared by diluting 1:50 a p-nitrophenylbutyratestock substrate (21 microL of p-nitrophenylbutyrate/mL DMSO) into MCbuffer immediately before use. Standard lipase (LIPOLASE™, NovozymesA/S, Bagsvaerd, Denmark) was prepared to contain 40 LU/mL of MC buffercontaining 0.02% AOS detergent. The standard was stored at 4° C. untiluse. Standard lipase was diluted 1/40 in MC buffer just before use.Using a plate reader, the absorbance at 405 nm was recorded as thedifference of two readings taken at approximately 1-minute intervals.Lipase units/mL (LU/mL) were calculated relative to the lipase standard.The results of the lipase assays for day 4 are shown in Table I andTable 2 relative to lipase activity obtained with pToC432 and pJaL676,respectively.

TABLE 1 Lipase expression by Aspergillus oryzae JaL294 transformantswith pToC432, pJaL700, and pJaL701 Plasmid # Transformants screened Meanlipase activity pToC432 2 1 pJaL700 2 1.77 pJaL701 2 1.52

TABLE 2 Lipase expression by Aspergillus oryzae JaL294 transformantswith pJaL676, pJaL724, and pJaL729 Plasmid # Transformants screened Meanlipase activity pJaL676 2 1.00 pJaL724 2 1.23 pJaL729 2 1.63

As shown in Table 1 where two different parts of the NA2 promotersequences are duplicated there was significant increase in expression oflipase for both constructions as compared to the wild type plasmid(pJaL485).

As shown in table 2 where a part of the NA2 promoter in pJaL676 has beenduplicated or triplicated there was significant increase in expressionof lipase for both constructions as compared to the wild type plasmid(pJaL676)—with the highest expression from the promoter that has beentriplicated.

Example 16 Construction of pJaL719

The Aspergillus expression plasmid pCaHj527 (WO 0070064) consists of anexpression cassette based on the Aspergillus niger neutral amylase IIpromoter fused to the Aspergillus nidulans triose phosphate isomerasenon translated leader sequence (NA2/tpi) and the Aspergillus nigeramyloglycosidase terminater (Tamg). Also present on the plasmid is theAspergillus selective marker amdS from Aspergillus nidulans enablinggrowth on acetamide as sole nitrogen source and the URA3 marker fromSaccharomyces cerevisiae enabling growth of the pyrF defectiveEscherichia coli strain DB6507 (ATCC 35673). Transformation into E. coliDB6507 using the S. cerevisiae URA 3 gene as selective marker was donein the following way:

E. coli DB6507 was made competent by the method of Mandel and Higa(Mandel, M. and A. Higa (1970) J. Mol. Biol. 45, 154). Transformantswere selected on solid M9 medium (Sambrook et. al (1989) Molecularcloning, a laboratory manual, 2. edition, Cold Spring Harbor LaboratoryPress) supplemented with 1 g/L casaminoacids, 500 micro g/L thiamine and10 mg/L kanamycin.

PCaHj527 was modified in the following way:

The NA2/tpi promoter present on pCaHj527 was subjected to site directedmutagenesis by a simple PCR approach.

Nucleotides 134-144 were altered from SEQ ID NO: 3 to SEQ ID NO: 4 usingthe mutagenic primer 141223 (SEQ ID NO: 5).

Nucleotides 423-436 were altered from SEQ ID NO: 6 to SEQ ID NO: 7 usingthe mutagenic primer 141222 (SEQ ID NO: 8).

The resulting plasmid was termed pMT2188.

The 6352 bp EcoRI-BamHI fragment from pMT2188 and the 617 bp EcoRI-BamHIfragment from pJaL676 where ligated together resulting in plasmidpJaL719.

Example 17 Construction of pJaL721

Plasmid pJaL721 is a derivate of pJaL719 where part of the NA2 promoterfrom position 7 to 510 has been duplicated. By PCR with primers SEQ IDNO: 15 and SEQ ID NO: 16 a 538 bp DNA fragment was amplified frompJaL676, purified, and digested with the restriction endonucleasesEcoRI, resulting in a 520 bp DNA fragment. The 520 bp DNA fragment wasligated together with the 6355 bp EcoRI DNA fragment from pJaL719,resulting in plasmid pJaL721.

Example 18 Construction for plasmid pPME/267

A strain of Aspergillus niger was used as a genomic clone of PME (pectinmethyl esterase) DNA supplier.

PCR reactions on Aspergillus niger genomic DNA was done with twofollowing primers which include a BglII and a XhoI restriction enzymesite, respectively.

(SEQ ID NO: 18) BglllaccPME-> atagatctaccatggttaagtcaattcttgca   Bgl II(SEQ ID NO: 19) XhoPME<- atctcgagaccgcttacaactttcacacaagt   Xho I

The reaction mixture comprised 2.6 ng/micro L of genomic DNA, 0.25 mM ofdNTP, 100 pmol of each primer and 3.5 units of EXPAND™ polymerase in 100microL of the provided buffer with MgCl₂. PCR was performed under thefollowing conditions: The reaction was submitted to 94° C. for 2 minutesfollowed by 30 cycles of 94° C. for 15 sec, 60° C. for 30 sec andextension at 72° C. for 1 minute. From cycle 11 to 30 the duration ofthe 72° C. extension step was prolonged with 20 sec per cycle. A finalextension step at 70° C. for 7 minutes followed by a 4° C. hold stepcompleted the program.

The amplified 1.3 kb PME gene was gel purified and ligated into pT7blueand the resulting plasmid was termed pt-vPME. pt-vPME was sequenced andconfirmed to be identical to EMBL:A34997.

To synthesize NA2 leader sequence, PCR amplification was performed usingthe primers rika1 (SEQ ID NO: 20) and rika2 (SEQ ID NO: 21). rika2includes a BamHI site.

rika1 (SEQ ID NO: 20):aaatactggcaagggatgccatgcttggaggatagcaaccgacaacatcacatcaagctctcccttctrika2 (SEQ ID NO: 21):atggatcccttctgtggggtttattgttcagagaagggagagcttgatgtgatgttgtcggttgctatcBamHI

The reaction mixture comprised 0.25 mM of dNTP, 100 pmol of each primerand 3.5 units of EXPAND™ polymerase in 100 microL of provided bufferwith MgCl₂. PCR was performed under the following conditions. Thereaction was submitted to 94° C. for 2 minutes followed by 30 cycles of94° C. for 15 sec, 60° C. for 30 sec and extension at 72° C. for 45 sec.A final extension step at 70° C. for 7 minutes followed by a 4° C. holdstep completed the program. The amplified DNA fragment encoding NA2leader was gel purified and named rika3.

To replace the TPI leader sequence of pJaL719 with NA2 leader, PCRamplification was performed using the primers rika3 which wassynthesized in the previous PCR reaction and rika4 (SEQ ID NO: 22). Thetwo primers contain the restriction site BamHI and EcoRI, respectively.

rika4 (SEQ ID NO: 22):  atgaattcatggtgttttgatcattttaaatttttat EcoR I

The reaction mixture comprised 10 ng of pJaL719 as template, 0.25 mM ofdNTP, 100 pmol of each primer and 3.5 units of EXPAND™ polymerase in 100microL of provided buffer with MgCl₂. The reaction was submitted to 94°C. for 2 minutes followed by 30 cycles of 94° C. for 15 sec, 60° C. for30 sec and extension at 72° C. for 45 sec. From cycle 11 to 30 theduration of the 72° C. extension step was prolonged with 20 sec percycle. A final extension step at 72° C. for 7 minutes followed by a 4°C. hold step completed the program.

The 0.6 kb amplified DNA fragment containing NA2 promoter region withthree extra amyR binding sites was cut by EcoRI and BamHI and ligatedinto pCaHj483 cut by EcoRI and BamHI and transformed to DH5-alpha. Thetransformants were then screened by restriction digesting of extractedplasmid DNA with EcoRI and BamHI followed by plasmid extraction andsequencing as described above for control of correct sequence. Theplasmid was named pHUda260 having A. niger NA2 promoter with NA2 leadersequences and three extra amyR binding sites, A. niger AMG terminatorand A. niduluns amdS gene.

The plasmid was linearized by SphI digestion. The 6.8 kb linearizedpHUda260 was filled-in by T4 DNA polymerase and digested with XbaI. The4.0 kb DNA fragment was gel-purified and ligated with 2.3 kb DNAfragment having Kozac sequences modified A. niger pyrG gene generatedfrom pHUda285 bp PmeI and SpeI digestion. The ligated mixture wastransformed into JM109. The resulted plasmid was pHUda263.

The tandem NA2 promoter region with three extra amyR binding siteswithout leader sequences was amplified from pJaL721 by PCR with theprimers NA2F and NA2R which included a Mfel and a EcoRI restrictionenzyme site, respectively.

(SEQ ID NO: 23) NA2F; 5′-tttcaattgaagcttatggtgttttgat-3′       MfeI(SEQ ID NO: 24)   NA2R; 5′-tttgaattcatacatcgcatcgacaagg-3′       EcoRI

The reaction mixture comprised 10 ng microL of pJaL721 as template, 0.25mM of dNTP, 100 pmol of each primer and 3.5 units of EXPAND™ polymerasein 100 microL of provided buffer with MgCl₂. The reaction was submittedto 94° C. for 2 minutes followed by 30 cycles of 92° C. for 1 min, 55°C. for 1 min and extension at 72° C. for 2 min. A final extension stepat 72° C. for 10 minutes followed by a 4° C. hold step completed theprogram.

The 1.0 kb DNA fragment was gel-purified and ligated into a pT7Bluevector. The ligation mixture was transformed into E. coli JM109. Theresulted plasmid (pHUda266) was sequenced. The amplified 1.0 kb fragmentwas confirmed that no changes had happen in the tandem NA2 promoterregion with three extra amyR binding sites without leader sequences. The1.0 kb DNA fragment having tandem NA2 promoter region with three extraamyR binding sites without leader sequences was obtained by EcoRI, Mfeldigestion and ligated into an EcoRI site of pHUda263 with Ligation high.The ligated mixture was transformed into JM109. The resulted plasmid waspHUda267.

The 1.3 kb fragment of PME gene was excised from pt-vPME by BglII andXbaI. It was ligated to pHUda267 cut by BamHI and XbaI. The resultingplasmid was termed pPME/267.

Example 19 Transformation of Aspergillus niger MBin119

Transformation of Aspergillus niger MBin119 can be achieved with generalprotoplasts methods. The preferred procedure for the invention isdescribed below.

The host strain is propagated in 100 ml of non-selective YPG medium at32□C for 16 hrs on a rotary shaker at 120 rpm. Cells are collected byfiltering, washed with 0.6 M KCl and resuspended in 20 ml of 0.6 M KClcontaining a commercial beta-glucanase product (GLUCANEX™, NovozymesA/S) at 600 microL/ml. The suspension is incubated at 32° C. at 80 rpmuntil protoplasts are formed, then washed twice with STC buffer. Theprotoplasts are counted with a hematometer and resuspended and adjustedin an 8:2:0.1 solution of STC:STPC:DMSO to a final concentration of2.5×107 protoplasts/ml. About 3 microgram of DNA is added to 100 microLof protoplast suspension, mixed gently and incubated on ice for 20 min.One ml of SPTC is added and the protoplast suspension is incubated for30 min at 37° C. After the addition of 10 ml of 50° C. Cove top agarose,the reaction is poured onto Cove-N agar plates and the plates areincubated at 32° C. for 5 days. As untransformed cells cannot grow onCove-N medium, transformants are easily selected.

Example 20 Analysis of Transformants

The A. niger host strain MBin119 was transformed with the expressionplasmid pPME/267 and selection positive transformants were isolated onCove-N agar. Transformants were isolated on Cove-N2 agar and grown at30° C. for 5 days and a piece of grown culture with agar was inoculatedto 100 ml of MLC. After cultivation on a rotary shaker at 220 rpm at 30°C. for 2 day, 10 ml of each culture was transferred to 100 ml of GO-50in shaking flask to cultivate at 30° C. for 5 days. Culture broth wascentrifuged at 3500 rpm for 15 minutes and the supernatant wascollected. The PME activity of the supernatant was determined asdescribed below. PME hydrolyses pectin methyl ester under constant pHand temperature. The activity of PME is determined as the amount oftitrant (0.050 N NaOH) consumed during neutralizing the liberatedpoly-galacturonic acid. Reaction mixture contains 0.48% (W/V) pectin and10 mmol Mg²⁺ (pH4.8). Reaction conditions are pH 4.8 and 30° C. One PEU(Pectin Esterase Unit) is the enzyme activity that produces onemilli-acid equivalent per minute under the conditions. A transformantshowed about 140 times higher yields than the parent A. niger strainused as a genomic DNA supplier (see Example 18).

1. A DNA sequence for regulating transcription of a structural geneencoding a polypeptide in an Aspergillus host cell comprising: i) afirst DNA sequence comprising nucleotides 7-510 of SEQ ID NO: 1, an RNApolymerase recognition site, and an Aspergillus nidulans triosephosphate isomerase leader sequence; and (ii) one or more additional DNAsequences comprising nucleotides 7-510 of SEQ ID NO:1 with or without anmRNA initiation site, wherein the first DNA sequence and one or moreadditional DNA sequences are operably linked to the structural gene, andwherein the first DNA sequence and the one or more additional DNAsequences comprise at least 3 Aspergillus amyR transcription factorbinding sites.
 2. The DNA sequence of claim 1, wherein the Aspergillushost cell is selected from the group consisting of A. niger,A. oryzae,A. awamori, A. foetidus, or A. japonicus.
 3. The DNA sequence of claim1, further comprising a third DNA sequence comprising nucleotides 7-510of SEQ ID NO: 1 with or without a RNA polymerase recognition site and/ormRNA initiation site.
 4. The DNA sequence of claim 1, comprising two ormore repetitive RNA polymerase binding sites located in tandem or wherethe RNA polymerase binding sites are closely linked.
 5. A DNA constructcomprising a DNA sequence of claim 1, operative in an Aspergillus hostcell and operably linked with a structural gene encoding a polypeptideand a terminator region.
 6. An expression vector comprising a DNAconstruct of claim 5, further comprising a signal peptide-coding region.7. An Aspergillus host cell comprising a DNA sequence of claim 4.